1. Field of the Invention
The present invention relates to an image pickup apparatus such as a video camera.
2. Description of the Related Art
In conventional image pickup apparatus such as video cameras, one known technique of automatic white balance adjustment is to perform feedback control such that, for example, color-difference signals become zero.
Under usual conditions where the image of an object is being picked up continuously, a state of illumination onto the object correctly reflects the image pickup operation. However, in some cases, a state of illumination onto an object cannot be identified. Such a problem occurs for example in a certain time period just after the power has been turned on. In this case, the white extraction should be performed over a wide range since there are various possibilities regarding the type of light source illuminating the object. The expansion of the white extracting range for a certain time period after an image pickup operation has been started causes an increase in time required to correctly adjust the white balance.
In view of the above problem, it is an object of the present invention to provide an image pickup apparatus having the capability of automatic white balance adjustment whereby the white balance can be quickly and correctly adjusted for an arbitrary object even just after the power supply has been turned on.
According to an aspect of the invention to achieve the above object, there is provided an image pickup apparatus comprising: image pickup means for converting an optical image of an object into an electrical image signal; a signal processing circuit for recording the image signal from the image pickup means; storage means for storing information about a state of the object obtained in process of recording; and control means for comparing a state of an object obtained immediately after turning on a power supply with the information stored in the storage means and for controlling an image pickup condition according to a comparison result.
According to another aspect of the invention, there is provided an image pickup apparatus comprising: image pickup means for picking up an image of an object; display means for displaying an output of the image pickup means; detecting means for detecting whether the object is being observed via the display means; storage means for storing a state of the object in response to an output of the detecting means; and control means for comparing a state of an object obtained immediately after turning on a power supply with the state of the object stored in the storage means and for controlling an image pickup condition according to a comparison result.
With the above arrangements according to the present invention, it is determined whether a new object to be recorded just after turning on the power supply is identical to the object that was recorded in the previous operation just before the power supply was turned off, and if the new object is almost identical to the previous object, an image pickup condition can be determined quickly by referring to the previous image pickup condition obtained just before the power supply was turned off.
Other objects and aspects of the invention will become more apparent from the following description of embodiments with reference to the accompanying drawings.